Power-transmission mechanism



.June'25; 1929. J. BRYANT 1,718,894

POWER TRANSMI S SION MEGHANI SM Filed Oct. 11, 1927 2 Sheets-Sheet l Patented June 25, 1929.

Jenner-WANT, or CARDIFF, wanna.

POWER-TRANSMISSION MECHANISM.

Application, filed October 11, 1927, Serial No.

ing oi a cam woriring in conjunction with two rollers carried on a reciprocating member and adapted to engage opposite sides of the cam simultaneously at all angular positions of the cam, characterized by the cam surface being constructed to give simple harmonic motion substantially described.

The member carrying the roller may be arranged to reciprocate in one or more guides. Two co-axial guides may be provided one on each side of the cam axis and adapted to guide the two ends of the roller carrying member respectively.

The guide maybe in the term of a cylinder havin a power transmitting or receiving piston connected to one end of the roller carrying member, and in the case where two co-axial guides are used each may be in the term of a cylinderhaving a power transmitting or receiving piston connected to one end 01' the roller carrying member.

The cylinder having the power piston may be that of an internal combustion engine, and. the cylinder having a power receiving piston may be that of a charge or air compressor.

The contour of the cam is a continuous curve generated by the points of contact of each oi: the rollers when the cam is rotating through one complete revolution and the roller carrying member reciprocating in a similar manner to that necessary to give simple harmonic motion. V

A. cam thus formed is symmetrical about the major axis but lines at different angles from edge to edge passing through the centre of rotation are not equal.

When employing the mechanism to convert a reciprocating motion to a rotary motion a force producing linear motion is applied to the roller carrying member, the external guides being held stationary.

The two extremities of the linear motion 225,516, and in Great Britain June 28, 1926.

representing each end of the stroke are reached when the points of contact between the two rollers and the cam periphery are in line with the centres of rotation of the 'am and rollers. This occurs ilior two angular positions of the cam, that is, when the cam has moved through 180. in all other positions the lines joinin the POIiITtt-l oi contact to the roller centres a re inclined to the line joining the roller centres which also passes through the centre of rotation of the cam. A torque 's thus applied to the cam thereby producing rotation oti the cam.

A further iieature oili the deviceis that a varying crank length el'lect is obtained asthe distance of the points of roller contact and the cam centre varies with angular movement of the cam. Due to this feature a more uniform torque is applied compared with the crank and connecting rod motion wherein the ratio of stroke to length of connecting rod is lixed.

It the cam be lined, and the external guides rotated, the roller carrying member will reciprocate whilst rotating.

i hatever the application of the mechanism, a pure rolling contact between the rollers and the cam periphery is ensured by limiting the length between the roller centres to some del'initc ratio oi? the stroke. litolling contact is destroyed and slip takes place be tween the rollers and the cam when the force causing angular acceleration of the rollers about their own centres overcomes the fric- L tional force of the points of contact. l-ligh roller accelerations are eliminated by arranging the cam contour or curvature without any change in sign, that is, without points of in flection in the curvature.

In applying the mechanism to in tern al zcombastion engines, two cylinders diametrically opposed may take the place oi. the guides for the roller carrying member, or the engine may be of the single cylinder type, and in applying the device to an engine having a row of cylinders the cams of the adjacent cylinders are arranged at dil'l'ereut angles on a common shaft.

' In the accompz'mying drawings l igure l, is

a diagram illustrating a method of forming the contour of the cam, Figure 2 a sectional front elevation of the mechanism applied to an engine having opposed co-axial cylinders, and Figure 3 is half of a vertical. side elevation of Figure 2.

In Figure 1 (31s the cam and lit- ,15%" the two rollers ofwhich the distance between the two centres 1' and 9- is invariable. The cam C is fixed on a shaft S.

In constructing the cam contour any convenient series of angular positions of the cam are taken. In the present case they are at intervals of 30, giving positions of the roller from its highest position to its lowest position 6. In use the rollers R R move along a line joining their centres, but to facilitate the construction "of the cam it is assumed'that the cam is stationary and that the centre line between the rollers takes up the various angular positions and at each of which it passes through the axis of the cam which in the present case is the axis of the shaft S.

On a line joining the centres of the rollers B R is the starting position 0. Describe a circle of radius h 0 'e' ual to half the desired stroke of the cam and Tom its centre It draw radiallines h 0, k to k at the same angular distances apart as radial lines 01 to 05 on the cam. 'Fr'om h draw a line h a perpendicular too it and from the axis 0 as centre and with 0, a v as radius draw a circular are cutting 0-l at l. From'the centre m on the line 0, c with radius m, 0 equal A; the desired strokes of the cam describe a circle, and on the radial line 01, draw'a perpendicular 0, k. Draw a line from the point is where the line 0, 70 cuts thiscircle to the centre 1 of the position of the roller afterits movement through the angle o, 0-1; this line will be found to cut the roller circle at a point of contact p which forms a point on the cam' surface. The

points p 17 p and p and any desired number of intermediate points are found in the same manner by taking a corresponding number of angular positions of the line joinin 'the centres of the roller R and R Iigures 2 and 3 illustrate a practical appliwhich move pistons 12, 12

cation of the mechanism. In this example two coaxial cylinders C and D form guides in These pistons which may be those of single acting internal combustion engines are connected by gudgeon pins or pivots 10, 11 to the opposite ends of a link or strap 12, the rollers I1 and R being mounted on these gudgeon pins and are thereby connected to opposite ends of the link 12. The link 12 is provided with a slot 13 so that it can reciprocate freely over a shaft 14 forming thepower shaft of the engine and which rotates in bearings 15 formed in the casing 16 of the engine. The link 12 is duplicated as 12 on the opposite side of the rollers R and R and these rollers engage the opposite sides of a cam 17 at all angular positions of the cam while a line through the centres of the rollers R and R also passes through the axis of the cam 17 which is the same as that of the shaft 14.

hat I claim and desire to secure by Letters Patent is Power transmission mechanism comprising a body having a pair of guide elements arranged in line with each other, a cam having a shaft mounted in bearings in said body and arranged between said guide elements, a link having a longitudinal slot through which said sh aft extends, a pair of reciprocating eh ments mounted in said guide elements and pivotally connected to the ends of said. link, and rollers mounted in said reciprocating element's, coaxial with the pivots of said reciprocating elements and engaging opposite sides of the periphery of said cam, the periphery of said cam being constructed to give a simple harmonic motion.

In witness whereof I afiix my signature.

JOHN BRYANT. 

